JPH0153526B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a vehicle-mounted radio receiver that tracks and automatically switches to the same broadcast content station.

Frequency data for several stations with the same broadcast content can be stored in the same channel selection button, and when you move out of the receiving station's service area, it will automatically switch to a station with the same broadcast content on a different frequency. Vehicle-mounted radio receivers are known. However, in this type of in-vehicle radio receiver, storing frequency data is a manual operation, which is extremely troublesome. For this reason, an automatic switching vehicle radio receiver has been proposed that searches for the same broadcast content station and automatically switches between them without the need for memory operations, and the present invention relates to this improvement. In other words, when audio muting is applied for a certain period of time even during normal reception, such as when turning on the power or switching bands, the entire band is searched and the receiving station at that time is captured in memory. This shortens the time it takes to acquire adjacent stations with the same broadcast content, making switching smoother. In the case of the present invention, a method is proposed in which when the synchronization of the presence or absence of demodulated output is detected several times in succession, it is determined that the content is the same. When the output lags for a certain period of time, the longer the period of lag in the demodulated output detected before that lag, the longer the period of lag can be expected. Based on actual measurements, when the demodulated output stagnates for a certain period of time, the second
The stations inspected by the searching means are also synchronously checked to see if the demodulated output has stopped. However, in the case of programs with few audio pauses depending on the broadcast content, there is a drawback that the time required to find a new station and to determine the content is extremely long. In order to improve this drawback, the present invention searches the entire band at the time of starting reception, such as when the power is turned on, and captures the receiving station in the memory. The idea is to make the transition extremely smooth. In most cases, the service areas of stations that transmit the same broadcast program on different frequencies intersect with each other by two or three stations, and adjacent stations with the same broadcast content may not receive sufficient reception sensitivity. Often possible. Therefore,
Capturing adjacent stations in memory at the start of reception as in the present invention is also effective in quickly finding new stations that appear due to movement, and is a very effective means. .

A detailed explanation will be given below with reference to the drawings. The figure shows one embodiment of the invention.

Antenna 1 is connected to tuner 2, and a received signal is supplied to tuner 2. A part of the signal tuned by the tuner 2 is given to the level determination circuit 3. This level determination circuit 3 detects the reception level of the reception signal of the broadcast station tuned by the tuner 2 at a plurality of predetermined levels, and supplies this level to the control section 5. Further, a part of the demodulated output of tuner 2 is given to demodulation level detection circuit 4 . The demodulation level detection circuit 4 detects a pause in the demodulated audio, for example, a pause period if the broadcast content is speech, and supplies this detection signal to the control unit 5. Further, the output of the tuner 2 is applied to a low frequency amplifier 9 via a muting circuit 8, amplified, and applied to a speaker 10.

Now, the data of the station currently being received is stored in the current station data area 6a of the current data memory 6, and this data is stored in the tuning voltage generation circuit 7.
The tuner 2 is tuned based on the output of the tuning voltage generating circuit 7. This tuning voltage generation circuit 7 is configured by, for example, a PLL frequency synthesizer. In operation, first, the tuning voltage generation circuit 7 generates a tuning voltage based on the frequency data of the data area 6a. And Chuyuna 2 is
Based on the tuning voltage given from this tuning voltage generation circuit 7, it tunes to the current station,
Receive broadcast programs. The received signal of the current station received by the tuner 2 is sent to the level judgment circuit 3.
Furthermore, the demodulated outputs are respectively given to a demodulation level detection circuit 4. The output of the level determination circuit 3 is accumulated and averaged by the control section 5, and is stored as the reception level of the current station. The output of the demodulation level detection circuit 4 is maintained for a certain period, for example, this period
When it detects this voice interruption, which lasts for about ms to several hundred ms, it performs the following series of actions.

First, the control unit 5 applies a muting signal to the muting circuit 8, and in order to prevent the generation of noise, the control unit 5 attenuates the audio level and interrupts the audio. Next, the frequency data stored in the current station data area 6a and the inspection station data area 6b of the current data memory 6 are exchanged, and the frequency data stored in the inspection station data area 6b is changed to the tuning voltage generating circuit. 7 to tuner 2. Chuyuna 2 is
Tune to that frequency and receive the corresponding station. Then, the reception level of the inspection station received by the tuner 2 is given to the level determination circuit 3, and the level is determined. The level signal determined by the level determination circuit 3 is provided to the control section 5. If this level is equal to or higher than a predetermined level, the control unit 5 stores the frequency data and reception level data of this station in the data area 11a of the memory device 11, and also stores the current station data area 6a of the current data memory 6 again. Frequency data and inspection station data area 6 stored in
The frequency data stored in b is replaced. Then, the control unit 5 transmits the muting signal given to the muting circuit 8.
Turn it OFF to cancel audio interruption. Next, the frequency data in the inspection station data area 6a is incremented (or decremented) by the minimum inter-station space. These operations are performed within several milliseconds to several tens of milliseconds, but since they occur at the moment when the audio is interrupted, they do not interfere with the broadcast reception of the current station. When there is a moment when the audio is interrupted again, a muting signal is given to the muting circuit 8 in the same manner as described above, the audio is interrupted, and the station corresponding to the frequency data in the data area 6b of the testing station is received. and determine its reception level. If this reception level does not reach a predetermined level, the current station is immediately returned and this station is not stored. Every time these operations are performed several times, the frequency data currently in the inspection station data area 6b of the data memory 6 is temporarily saved in the control section 5, and the stations stored in the memory device 11 are moved to the inspection station data area 6b. , a similar reception level check is performed, but if there is a station whose reception level exceeds the reception level of the station currently being received, the broadcast program for this station is determined as follows. In other words, switch to this station,
At the same time as the reception level is taken in from the reception level judgment circuit 3 to the control unit 5, the output of the demodulation level detection circuit 4 is checked.Although there is some time delay, it is the same as the current station based on the expected value regarding audio interruptions described later. If the audio is interrupted, it is determined that there is a possibility that the broadcast content is the same, and this station is left in the inspection station data area 6b. Now, the next time there is an audio interruption, we will test this station again, and if the same audio interruption occurs several to ten times, it will be determined that the broadcast content is the same and we will switch from the current station to this station. . In this way, when the reception level check for the frequency data in the memory device 11 is completed, the frequency data saved in the control unit 5 is returned to the inspection station data area 6b, and
The search for newly received stations continues while changing the data sequentially. Now, when the data area of the memory device 11 becomes full in this way, this time,
Data areas 11a to 11 in memory device 11
The lowest reception level of h is compared with the reception data of the newly found station, and if the reception level of the newly found station is higher, it is replaced with new data. As a result, only recently received signals with good reception levels remain in the memory device 11. When the current station becomes weak, stations with the same broadcast content are discovered in the memory device 11 using the method described above, and the stations are switched one after another. It is possible to always track the same broadcast content station in good condition without having to perform a channel selection operation. By the way, in this method, when moving and entering the service area of a new broadcasting station, the most important point is to quickly capture this broadcasting station in the memory and not to interfere with the broadcast reception of the current station. be. For this reason, it is extremely effective to capture the current neighboring stations in memory when reception starts. Furthermore, as a result of statistical measurements of audio interruptions in broadcasting, the following was found. In other words, regarding the amount of time that audio continues to be interrupted after a certain period of audio interruption is detected, the longer the period of audio interruption that is detected first, the longer the expected value of the period of time that the audio will continue to be interrupted. It is. For example, to show an example of experimental value, 85ms
When an audio interruption is detected, there is a 90% chance that it will continue for about 10ms, and
When a 200ms audio interruption is detected, it is approximately
It was 35ms. Judgments about broadcast content are made based on such probabilistic facts.
Even if the time when broadcast audio is output is equal to the time when it is not, if it is detected that audio interruption occurs at the same time n times in a row, the probability that it is different broadcast content is (1/2) ⁿ . , n=10, it is less than 0.1%. It has also been confirmed that even if the audio is interrupted at a point where 90% or more of the audio interruptions can be expected to continue, if the interruptions are not frequent, there will be little impact on broadcast reception and there will be no problem. That is, for a certain interval e.g. 1
If you check the inspection station only when both the requirements of setting intervals of about seconds and detecting audio interruptions over a certain period of time are satisfied, you can check other stations with little effect on the broadcast reception of the current station. This means that it is possible to check the level of In addition, when a long interruption time is detected as mentioned above, the expected value of the continuing interruption time becomes long, so if audio interruption continues at a certain interval, the station to be inspected according to the interruption time. It is also possible to increase the number of

Needless to say, it is very advantageous to quickly search all bands and capture new stations in this way.

As described above, according to the present invention, when a certain broadcasting station is selected, an in-vehicle radio receiver is realized that automatically selects a station with the same content and a good reception level and switches to the next station. It can provide a very effective means.

[Brief explanation of drawings]

The figure is a block diagram showing an embodiment of the in-vehicle radio receiver of the present invention. In the figure, 1 is an antenna, 2 is a tuner, 3
is a level judgment circuit, 4 is a demodulation level detection circuit, and 5 is a level judgment circuit.
is the control section, 6 is the current data memory, 6a
1 is a current station data area, 6b is a detection station data area, 7 is a tuning voltage generating circuit, 8 is a muting circuit, 9 is a low frequency amplifier, 10 is a speaker, 11 is a memory device, and 11a to 11h are data areas.

Claims (1)

[Claims] 1 A tuner that tunes to a desired station from among multiple stations and receives the transmitted signal from that station, and a tuner that searches for stations other than the desired station within the reception band and obtains the tuning data and reception level of the searched station. a first search means for storing in a memory a station searched for by the first search means when the memory becomes full; and a station with the lowest reception level among the stations stored in the memory; storage means for comparing the reception level of the station with the higher reception level and storing the tuning data and reception level of the station with the higher reception level in the memory; a second search means for searching for a station with a high reception level, and then searching whether a station whose reception level is higher than the station being received has the same program content as the station being received; and this second search means and a control means for continuously operating at least the first search means when starting reception within the predetermined reception band. Machine.